Electron discharge device and process of making the same



FIP8303 No Drawing.

X-R hewy zr Patented Mar. 15, 1932 ATE. T FFIQE FREDERICK L. HUNTER, JR,OF TOWACO, NEW JERSEY, ASSIGNOR TO BE FOREST RADIO TELEPHONE & TELEGRAPHCOMPANY, OF JERSEY CITY, NEW JERSEY, A CORIPOBA- TION OF DELAWAREELECTRON DISCHARGE DEVICE AND PROCESS OF MAKING THE SAME Applicationfiled. May 10,

This invention relates to electron discharge devices and the process ofmaking the same, and more particularly to the means and method forreducing the residual gases and activating the filament. x

The objects of the invention are to provide an improved means and methodof reducing the residual gases and activating the filament inan electrondischarge device; to use a flashing material which may be readilyhandled without detriment to the material or injury to the operator; toprovide a material which can be flashed and which will have maximumeffect; to employ the element iodine as a :filash- :ing material; toalso employ potassium as a flashing material to utilize asalt asthekfiashing material; to obtain a decomposition of the saltin order toeffect .a flash of the tube; to

same is being pumped .so as to reduce the residual gases and obtain ashigh a degree of evacuation as possible. 7

Preferably the material which is employed for flashing the-electrondischarge device in accordance with the present invention is -a saltwhich may be decomposed into one or more active materials which in thefree state will be active as a flash at a much lower temperature thanmagnesium.

I have known of the desirability of potassium and iodine as flashingmaterial, but heretofore have not been able to commercially use the samefor the reason that they are very diflicult to handle in a free stabeing both injurious to the operator and difiicult to control. I nowfind that by utilizing a salt of one or both of these materials that Ican handle the saltvery readily and without injury. The salt may bedecomposed within the 1924. Serial No. 712,456.

electron discharge device at the time and place desired and at such timethe free element will efiect a reduction of the residual gases. I" havefurther found that it isnot only possiblebut advantageous to employ asalt containing both the element potassium and the element iodine-suchas potassium i0- dide. WVhen these two elements are liberated in thefree state, they are exceedingly active and effective.

In order todecompose the salt-of potassium and iodine, I find that analloy of magnesium and calcium'associated therewith, and heated, willhave a disrupting effect-upon the salt and cause the same toseparateinto its constituent elements. The use of this alloy ofmagnesium and calcium is doubly [advanitageous because .it not onlydecomposesthe saltybut also operates to combine-with oxygen and activatethe filament by reducing the oxide coating thereon so the -filament willhave an exposed surface of free metal. 1 Here it is to be understoodthat filaments such as the frequently-used mixture orj coatingof thoriumfreely'oxidize when exposed tothe v air and will almost-invariably.be-applied to the-electron discharge device as thorium 0X- .ide. It hasalways been necessaryto change at least a portion of the oxide beforethefilament can be made to emit electrons. Use of thealloy above mentionedtherefore accomplishes this purpose as well as decomposing the saltabove mentioned. x

In use, I prefer to mixthe alloy and salt in powder form, although it isdeemed within the scope of the invention to associate" the alloy'andsaltin any. manner which will cause the one to react upon the other at thedesired time. The mixture in powder form can be secured to theplateofthe-electron discharge device in any suitable "manner as by useof paste or mechanical agencies. The specific manner in which themixtureis secured or held not being part of the present invention, no furthermention need be made thereto at this time.

In carrying out the process which :I have invented the salt and alloyare preferably mixed and applied to the plate during the course ofmanufacture, and while the tube is on the pump being evacuated, thetemperature of the alloy is raised by any suitable means, such aselectron bombardment, and the temperature being suflicient, the alloyflashes or vaporizes, acting upon the salt to break it up into itsconstituent elements which likewise flashes or vaporizes, both operatingto reduce the residual gases in the tubes so as to improve the degreeofevacuation therein.

Obviously detail changes and modifications may be made in themanufacture of my improved electrondischarge device, and process bywhich the same is made, and I do not wish to be understood as limitingmyself to the exact combination of elements or other like matter or tothe exact steps and process mentioned, except as set forth in thefollowing claims when construed in the light ,of the prior art.

Having claim:

1. The method of manufacturing an evacuated electron discharge devicehaving an electron .emissive cathode, which comprises introducing achemical compound of potassium and iodine in the presence of an alloy ofmagnesium and an alkaline-earth metal into the device and heating saidchemical compound to liberate the elements thereof so that they mayreact with the gases within the device. v

2. In the method of manufacturing electron discharge devices comprisinga vessel and a plurality of electrodes therein including the steps ofintroducing a chemical compound of potassium and iodine into the vesseland an alloy containing magnesium and an alkaline-earth metal andheating said alloy to break it down and cause it to act upon saidchemical compound to break it up into its constituents.

3. In the method of manufacturing electhus described my invention, I

tron discharge devices comprising a vessel,

and a plurality of electrodes therein including the steps of introducinga chemical compound of potassium and iodine into the vessel and an allowof magnesium and calcium and heating said alloy to disrupt it.

4. In the method of manufacturing electron discharge devices comprisinga vessel and a plurality of electrodes therein including the steps ofintroducing a chemical compound of potassium and iodine into the vessel,and an alloy of calcium and magnesium and heating said alloy to disruptit and effect decomposition of said chemical compound.

5. The herein described process which comprises heating an alloycontaining magnesium and an alkaline-earth metal in the presence of asalt containing iodine in an evacuated vessel and heating the alloywhile in said vessel.

6. The method of manufacture of electron discharge devices comprisingthe steps of introducing into the envelope of the device a halidecontaining iodine and an alloy containing magnesium and analkaline-earth metal, and flashing magnesium alloy to produce a freehalogen for cleaning up residual gases within the device.

7. The method according to claim 6 in which the magnesium alloy isflashed by heatmg.

S. In the manufacture of electron discharge devices the method ofliberating a free halogen within the envelope of the device whichcomprises heating an alloy of magnesium and calcium in the presence of ahalide within said envelope.

9. In the manufacture of electron discharge devices the method ofreducing residual gases which comprises introducing a halogen salt andan alloy containing magnesium and an alkaline-earth metal into theenvelope of the device, and flashing the alloy to liberate a free halidefrom the salt.

10. In the manufacture of electron dis- 'charge devices the method whichcgmprises introducing into the interior of the envelope of the device aquantity of salt containing i0- dine and an alloy containing magnesiumand an alkaline-earth metal and flashing the alloy in the presence ofsaid salt to liberate free iodine.

11.' The method according to claim 10 in which the alloy is flashed byelectron bombardment. i

12. The method according to claim 10 in which the'alloy containscalcium.

13. The method according to claim 10 in which thesalt contains potassiumand iodine.

14. The herein described process of producing free iodine whichcomprises introducing an alloy containing magnesium and calcium and asalt containing iodine into the evacuated vessel, and flashing the alloyto disrupt the salt and produce free iodine.

15. The process according to claim 14 in which the alloy is flashed byheat.

16. An electron discharge device comprising an evacuated envelope, aquantity of alloy containing magnesium and an alkalineearth metal, and asalt of iodine applied to a portion of the interior of the envelope.

FREDERICK L. HUNTER, J R.

